Welcome to the next PoreLab lecture!
Who: Prof. Francisco Vega Reyes from the department of Physics at the University of Extremadura (Spain)
When: Wednesday 28 August at 13:00 (Norway time).
Where: The lecture will be in-person in the Kelvin room (PoreLab Oslo) and will be streamed in the common room (PoreLab Trondheim). From anywhere else, you will be able to join via the following Zoom link:
https://uio.zoom.us/j/65837085049?pwd=WjZianUyN3FJa2liQkxBbzQrOCtGdz09
Title: The properties of fluctuations for a two-dimensional chiral particle
Abstract:
We study here the microscopic fluctuations in a two-dimensional fluid of chiral particles, by means of the experimental data we obtained for a system of air-fluidized disk-shaped rotors. We showed in a previous work that, under certain circumstances, a fluid composed of this type of particles can display odd diffusion (see Figure 1) and strong velocity correlations between translations and rotations [1].
We present also measurements of the diffusive dynamics of a single chiral particle, and of measurements of the rotational diffusion coefficient. These new results allow us to separate interparticle collision effects out of the inherent diffusive dynamics of a chiral particle. We analyze here to what extent the dynamics of the single chiral particle can depart from the typical behavior of a Brownian particle [2]. In particular, we assess if the generalized Langevin equation and the fluctuation-dissipation theorem [2, 3] are fulfilled here. We discuss how the presence of inherent correlations between translations and rotations can have an impact on this question. Our results should be significant for the development of a theoretical framework for the dynamics of a chiral particle, and active matter in a broader context.
Figure 1: Left: Brownian-like trajectory (vanishing odd diffusion). Right: A particle trajectory where
odd diffusion is predominant. The trajectory of one particular particle is highlighted in color in both
cases. Color fades from blue, at early times, to yellow as the trajectory ages.
References
[1] F. Vega Reyes, M. A. L´opez-Casta˜no, and A. Rodr´ıguez-Rivas, Commun. Phys. 5, 256 (2022).
[2] R. P. Ojha, P.-A. Lemieux, P. K. Dixon, A. J. Liu, and D. J. Durian, Nature 427, (2005).
[3] R. Kubo, Rep. Prog. Phys. 29, 255 (1966).